A KINETIC-STUDY OF THE ELECTROCHEMICAL VAPOR-DEPOSITION OF SOLID OXIDE ELECTROLYTE FILMS ON POROUS SUBSTRATES

The electrochemical vapor deposition (EVD) method is a very promising technique for making gas-tight dense solid electrolyte films on porous substrates, In this paper, theoretical and experimental studies on the kinetics of the deposition of dense yttria-stabilized zirconia films on porous ceramic substrates by the EVD method are presented. The more systematic theoretical analysis is based on a model which takes into account pore diffusion, bulk electrochemical transport, and surface charge-transfer reactions in the film growing process. The experimental work is focused on examining the effects of the oxygen partial pressure and substrate pore dimension on the EVD film growth rates. In accordance with the theoretical prediction, the pressure of oxygen source reactant (e.g., water vapor), the partial pressure of oxygen and substrate pore dimension are very important in affecting the rate-limiting step and film growth rate of the EVD process. In the present experimental conditions (e.g., low pressure of oxygen source reactant and small substrate pore-size/thickness ratio), the diffusion of the oxygen source reactant in the substrate pore is found to be the rate-limiting step for the EVD process. © 1990, The Electrochemical Society, Inc. All rights reserved.